/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or (at
 *    your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful, but
 *    WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/*
 *    FloatingPoint.java
 *    Copyright (C) 2002 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core.matrix;

import weka.core.RevisionHandler;
import weka.core.RevisionUtils;

import java.text.DecimalFormat;
import java.text.FieldPosition;

/**
 * Class for the format of floating point numbers
 * 
 * @author Yong Wang
 * @version $Revision: 1.4 $
 */
public class FloatingPointFormat extends DecimalFormat implements
		RevisionHandler {

	/** for serialization */
	private static final long serialVersionUID = 4500373755333429499L;

	protected DecimalFormat nf;
	protected int width;
	protected int decimal;
	protected boolean trailing = true;

	/**
	 * Default constructor
	 */
	public FloatingPointFormat() {
		this(8, 5);
	}

	public FloatingPointFormat(int digits) {
		this(8, 2);
	}

	public FloatingPointFormat(int w, int d) {
		width = w;
		decimal = d;
		nf = new DecimalFormat(pattern(w, d));
		nf.setPositivePrefix(" ");
		nf.setNegativePrefix("-");
	}

	public FloatingPointFormat(int w, int d, boolean trailingZeros) {
		this(w, d);
		this.trailing = trailingZeros;
	}

	public StringBuffer format(double number, StringBuffer toAppendTo,
			FieldPosition pos) {
		StringBuffer s = new StringBuffer(nf.format(number));
		if (s.length() > width) {
			if (s.charAt(0) == ' ' && s.length() == width + 1) {
				s.deleteCharAt(0);
			} else {
				s.setLength(width);
				for (int i = 0; i < width; i++)
					s.setCharAt(i, '*');
			}
		} else {
			for (int i = 0; i < width - s.length(); i++)
				// padding
				s.insert(0, ' ');
		}
		if (!trailing && decimal > 0) { // delete trailing zeros
			while (s.charAt(s.length() - 1) == '0')
				s.deleteCharAt(s.length() - 1);
			if (s.charAt(s.length() - 1) == '.')
				s.deleteCharAt(s.length() - 1);
		}

		return toAppendTo.append(s);
	}

	public static String pattern(int w, int d) {
		StringBuffer s = new StringBuffer(); // "-##0.00" // fw.d
		s.append(padding(w - d - 3, '#'));
		if (d == 0)
			s.append('0');
		else {
			s.append("0.");
			s.append(padding(d, '0'));
		}
		return s.toString();
	}

	private static StringBuffer padding(int n, char c) {
		StringBuffer text = new StringBuffer();

		for (int i = 0; i < n; i++) {
			text.append(c);
		}

		return text;
	}

	public int width() {
		if (!trailing)
			throw new RuntimeException("flexible width");
		return width;
	}

	/**
	 * Returns the revision string.
	 * 
	 * @return the revision
	 */
	public String getRevision() {
		return RevisionUtils.extract("$Revision: 1.4 $");
	}
}
